Charles Mackay - The Lost Beauties of the English Language (1874)
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Scottish journalist and author Mackay's best-remembered work is 1841's Extraordinary Popular Delusions and the Madness of Crowds which has been in print seemingly since its first publication. Among the long list of his other works is this collection of archaic and disappearing words that he would like kept alive. The result is a fascinating dictionary though so many included words are too archaic to be successfully revived - if Piers Ploughman is your most recent source maybe it's time to let it go into that gentle linguistic night. To be honest, though, this book isn't quite as interesting as some of the slang dictionaries I've posted since Mackay favors words that are blunt and craggy (not quite "beauties") with meanings that seem almost arbitrary. Older thieves' lingo I can see still being used even if for comic effect but it's a lost cause to bring back "scorse" (to exchange) or "unsneck" (bolting a door).